Yes, you do need certain code to post a .swf (flash) file. Here's an example of the code required to post. Bear in mind this code is generated by Dreamweaver so it might not be the cleanest, best code out there; but it will work (alter size numbers to fit your flash file):
<object classid="clsid: D27CDB6E-AE6D-11cf-96B8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,29,0" width="800" height="330">
<param name="movie" value="file:///filedirectoryhere/yourflashfile.swf" />
<param name="quality" value="high" />
<embed src="file:///filedirectoryhere/yourflashfile.swf" quality="high" pluginspage="http://www.macromedia.com/go/getflashplayer" type="application/x-shockwave-flash" width="800" height="330"></embed></object>